1) Field of the Invention
The field of this invention relates to recycling of certain waste and more particularly to recycling of latex paints and other similar materials to be utilized as an ingredient in Portland cement which is then to be used to produce concrete building materials.
2) Description of the Prior Art
The process of this invention is to be discussed specifically in conjunction with a latex paint. However, it is considered to be within the scope of this invention that the process could be utilized with other products such as water-based paint, water-soluble pigments, resists and water-soluble adhesives.
Latex paint is in exceedingly common usage not only by the general public but also by businesses. In recent years there has been a direction of movement from solvent based paint to the latex type of paint. The main objection to a solvent based paint is to its emission within the air of a petroleum based substance which when breathed is believed to be damaging to humans and is also potentially explosive. The result has been a substantial increase in the volume of usage of latex paints which similarly increased the waste of latex paint.
Whenever a decision is made to paint a given structure, invariably there will be provided an amount in excess of that which is actually needed. This excess becomes waste. This waste usually ends up being thrown away. The disposing of latex paint within landfills is being objected to which has resulted in increasingly restrictive state, local and federal regulations. These regulations are requiring that latex paint waste is to be handled as a hazardous waste. Disposal of a hazardous waste is an extremely expensive procedure.
Concrete building materials are manufactured in a substantial amount throughout the world. The manufacturing of a cement building material consists of a combination of an inert substance such as sand, a binder and water. The binder is typically called Portland cement. The cement reacts chemically with water to set and harden through chemical reactions.
Portland cement is a type of hydraulic cement in the form of a finely divided, gray powder composed of lime, alumina, silica and iron oxide. Small amounts of magnesium, sodium, potassium and sulfur are also present. The cement may be modified to include a plasticizer to improve adhesion, strength, flexibility and curing properties.
Cement can be manufactured by either a wet process or in a dry process. Where the raw materials have a high moisture content (such as chalk and clay), the wet process is used. The dry process is used for harder raw materials such as limestone and shale. In both processes the resulting mixture is burned generally within a kiln. The burning process can be either by calcining, roasting or autoclaving with calcining being commonly used. The operating temperature of the heat is generally about 2600 degrees Fahrenheit. During the heating process the mixture is partially fused forming lumps referred to as cement clinker. The cement clinker is then ground to the fine dry powder which is known as Portland cement. During grinding of the cement clinker, the cement may be modified to include a plasticizer or to include other specialty type of ingredients.
There are a number of mineral-based solid materials that are chemically compatible for use as an ingredient in the manufacture of Portland cement and other concrete products. These mineral-based solid materials are not typically utilized due to not being readily available to the manufacturer of the cement. Examples of such materials that are not utilized but would work satisfactorily are listed under the Detailed Description of the Preferred Embodiment.
The present invention differs from the prior art in that the product of this invention is added during the final grinding with the clinker and is not processed through the calcination portion of the manufacturing process, is not claimed to be used in the formulation or manufacture of cement clinker, and is not claimed to have fuel value. The prior art references of Pennell U.S. Pat. No. 4,081,285; Rigby et. al. U.S. Pat. No. 523,645; Babcock-Hitachi JP 357027954; Zaporozhe Titanium and Magnesium Complex, Krivoi Rog Cement Works DE A 2839829 and Cement Ind. Res. Inst. collectively address use as feed into the kiln for combining with other raw materials in clinker formation or fuel for the calcining process. The important distinction between the present invention and these citations is in the chemical transformations that occur when the raw feed materials are introduced to temperatures of calcination (about 2600.degree. F. for a period of up to three hours).
The present invention differs from other citations such as Chapple U.S. Pat. No. 4,116,705, Sherwood et. al. U.S. Pat. No. 4,383,928, Wichner et. al. U.S. Pat. No. 5,167,711, Brunbeck et. al. U.S. Pat. No. 4,454,048, Koumal U.S. Pat. No. 5,286,427, and Hitachi Shipbld Engg KK JP A 0019472 in that the latex paint is claimed to be used in the manufacture of Portland cement rather than used in concrete or concrete products which uses Portland cement to form a monolithic structure. The cementaceous reactions that occur when Portland cement is hydrated involves chemical reactions that form a solid monolithic matrix and is the basis for all concrete technology. The present invention is that the latex paint is in a product that when ground with the clinker and gypsum enhances the performance of the resultant concrete and it is not claimed as a treatment process or a method for solidifying, immobilizing, or similar method of incorporation of the waste into a concrete matrix. None of the prior art discusses enhancement of strength or plasticity in the Portland cement when used for treatment processing or formation of the solidified mass that is used as a building material (see Sherwood U.S. Pat. No. 4,383,928). Strength enhancement and plasticity are part of the attributes of the product additive of the present invention.
The present invention is more similar to that of Kuhlmann EP 537411, Zhangabylov et. al. "Coagulation of Divinylstrene Latex in Suspensions of Portland Cement and Its Mineral Studies in Connection with Strengthening Oil Wells", Tr. Inst. Khim. 1971, Isenburg et. al. "Hypothesis for Reinforcement of Portland Cement by Polymer Latexes", J. Amer. Ceram. Soc. 1974, Vess U.S. Pat. No. 4,725,632, Eash 4,202,809, and Ceska U.S. Pat. No. 4,398,957, who claim that the use of latex additives enhance Portland cement performance. The additives consisting of finely divided latex (or chemically similar materials in a water media) solids are added to the Portland cement either at the work site or formulated with the Portland cement. The use of the latex paint additive of this invention acts in a similar fashion, replacing the virgin materials noted in these references. The novelty of the present invention is that the latex paint additive is derived from waste latex paints or chemically similar materials.
The foregoing mentioned references were cited and applied in the parent applications U.S. Ser. Nos. 08/217,276, 08/057,177 and 08/403,077.